The present invention relates to improvements in co-generation systems, and more particularly in systems that can be used in domestic or small commercial settings.
Co-generation is generally defined as a process where an engine is used to generate both heat and electrical power. It also generally refers to the use of the waste heat from the engine as the source of heat for space heating of the dwelling in which the process occurs. Also, the space heating is either by use of hot water in space heaters or by forced air heaters.
Example of prior art of co-generation system can be seen in U.S. Pat. No. 4,680,478 (Wicks) and subsequent articles in Popular Science, such as xe2x80x9cHome-size Co-generatorxe2x80x9d by V. Gilmore, on this invention by Wicks. The co-generation system disclosed uses an internal combustion engine and a forced air heat exchanger. However, as discussed by Meijer in U.S. Pat. No. 5,074,114, such engines have a short life and high maintenance costs.
Alternatives to the internal combustion engine in such a co-generation system were discussed in the publication xe2x80x9cStirling-Cycle Machinesxe2x80x9d by G. Walker (Oxford, 1973). This discloses the Stirling engine and gas turbine as alternatives to the internal combustion engine in co-generation systems.
Meijer also discloses a co-generation system with a Stirling Cycle engine. Meijer addresses some of the above problems, disclosing a system in which the Stirling engine can run on one of a variety of fuels, in which excess electricity can be sold to the national grid or local power network; and in which a heat exchanger is added to recover heat from the exhaust gases of the engine, for use in space heaters and the like.
However there are two problems of co-generation systems that are not addressed in any of the known co-generation systems disclosed above. The first of these is the sometimes unacceptable noise and vibration of the engine within the system. This is of especial concern where the co-generation system is set within a domestic dwelling or small commercial building. Further, none of the prior art discloses a system that is of a size to be usable in a mobile situation, for example, in a vehicle designed for living in, or a yacht. An aircraft is also a possible vehicle.
Also, at present the disclosed, known methods of co-generation mainly use open systems in heat reticulation. One partially closed system is disclosed in Meijer. However this closed system uses only a forced air heater, or an air conditioner. Extensive systems of heat usage with water, and water or air reclamation, are not disclosed.
An object of the present invention is the provision of a co-generation system for a domestic or commercial building, being a system which includes a water storage tank, whereby the system provides for secondary heat recovery from the engine, and provides means for reduction in the vibration and noise of the engine used. A further object of the present invention is the provision of a co-generation system whereby the storage tank for the coolant water and the coolant water itself are used for the secondary heat exchange and as the means to reduce the noise and vibration of the engine.
A yet further object of the present invention is the provision of a co-generation system that takes up no more room than a hot water storage tank.
Another object of the present invention is to address the problems discussed above, or at least to provide the public with a useful choice.
Further aspects and advantages of the present invention will become apparent from the ensuing description which is given by way of example only.
The present invention provides a co-generation system for producing heat, hot water, and electricity, said system being contained within a building and said system comprising:
an engine with a burner and an electric generator;
a tank for storage of primary water,
means for circulating said primary water about said engine;
means for venting exhaust gases from said engine to the outside of the building housing the co-generation system, said means including a first heat exchanger for cooling said exhaust gases;
means for circulating the primary water to and from the first heat exchanger to produce said heat;
means for directing said heat to space heaters; and wherein the improvement comprises:
the water storage tank being adapted to contain therein the engine and generator in fluid isolation from the primary water within the storage tank, said tank and primary water providing means to reduce noise and vibration of the co-generation system.
According to another aspect of the invention there is provided a co-generation system as described above, wherein said means for directing heat includes a second heat exchanger, wherein said second heat exchanger heats secondary water. If hot water is to be drawn from said system, the hot water is either the primary water or the secondary water.
According to another aspect of the invention there is provided a co-generation system as described above, in which the system is usable in mobile buildings. For the purposes of this specification, the term xe2x80x9cmobile buildingxe2x80x9d is used to define, but is not limited to, movable dwellings, movable homes or vehicles, yachts, and the like.
Optionally, the hot water drawn from the system is potable. Optionally, said tank is also a primary heat exchanger from the exhaust gas to the primary water. Preferably the storage tank includes a cavity which is adapted to contain the engine and generator.
Preferably, said engine is a Stirling engine. Preferably, said engine is a Stirling engine which can operate on one of a plurality of fuels. Preferably, the system also includes a heat sink or heat exchanger that can be used to transfer excess heat out of the system when the system is required for electricity generation only, and not for heat generation.
Optionally, the system also includes the ability to transfer excess electricity to the national power grid or to another power storage facility (for example, battery storage of known type) when only heat is drawn from the system.